Flip-flop-sandal

ABSTRACT

A flip flop sandal having a shoe sole and a big toe compartment for separately accommodating the big toe to separate the big toe from the other toes so as to orthopedically correct and/or prevent hallux valgus. The flip-flop sandal includes a metatarsal strap for supporting the metatarsus that is connected to the shoe sole by a centering apparatus in a pre-determined orientation, the metatarsal strap including lateral foot sole support segments that extend laterally under the foot sole and over the shoe sole so as to be lifted up relative to the shoe sole in order to support the metatarsus from the foot sole with upwardly oriented lateral pressure so as to support the metatarsus in the upright position even when the foot sole lifts up from the shoe sole during a rolling movement of the foot which occurs when a wearer is walking.

BACKGROUND OF THE INVENTION

The present invention relates to a sandal, and in particular a flip-flop sandal, having a shoe sole and a big toe compartment for separately accommodating the big toe. In this way, the invention thus relates in particular to flip-flops having orthopedic means for correcting and/or preventing hallux valgus.

Painful defective positioning of toes that frequently must be treated surgically can result from various causes, especially wearing shoes that are too tight or too high. In particular, the big toe frequently moves into a bent defective position towards the outside of the foot, and this is associated with changes in the tissue in the area of the metatarsophalangeal joint or the metatarsus.

To correct such defective toe positioning, especially hallux valgus, normally a corrective splint is applied to the foot to correctively bend or force the toe into its proper position and hold it there. Appropriate splints are used both post-operatively and during conservative therapy.

However, sometimes there is a reluctance to wear such foot splints, especially in the summer in open shoes like sandals because the splints are visible when socks and stockings are not worn and, as such, sometimes there is the perception of a stigma associated with wearing them.

In the framework of such therapies for toe correction there has been a growing understanding that it is important to strengthen the muscles in the foot region, especially muscles that are frequently atrophied, to allow the foot to be able to permanently hold itself in the proper shape even without splints. Since appropriate exercises that are performed deliberately during physical therapy frequently are often perceived as bothersome and are not continued for long, it would be desirable to have a shoe that trains the foot automatically so as to build up the foot's muscles, especially in the metatarsal area, and hold the big toe in its proper natural position, while permitting appropriate movements to attain the desired exercise effect.

SUMMARY OF THE INVENTION

Thus, the object of the underlying invention is to create an improved sandal of the aforesaid type that does not suffer from the disadvantages of the shoes of the prior art and that further advantageously refines these shoes. In particular, a flip-flop sandal is provided that supports therapy for hallux valgus and prevents deformation of the foot so that when walking the big toe is held in its proper natural position and at the same time support is provided to the arch of the foot. Also, the sandal of the present invention attains more vigorous exercising of the foot muscles in the metatarsal area that control movement of the big toe.

The shoe sandal of the present invention enables centering of the sandal sole relative to the foot and in a certain orientation in order to prevent the lateral slipping and twisting that is normally experienced with flip-flops so that the big toe compartment acts like a corrective toe positioning aid and keeps the big toe in its proper natural position so as to exert a corrective force that maintains proper alignment of the big toe. The shoe sole is centered using a specially configured attachment of the shoe sole in the metatarsal area which simultaneously supports and aligns the metatarsus. In accordance with the invention, the flip-flop has a metatarsal strap for supporting the metatarsus such that the strap is attached to the shoe sole in a predetermined orientation by means of a centering apparatus, the aforesaid metatarsal strap having lateral foot sole support segments that extend laterally underneath the foot sole and over the shoe sole and are raised from the shoe sole in order to support the metatarsus so that the foot sole is held thereon and upwardly oriented, lateral pressure forces are exerted thereon in order to support it in the upright position, even when the sole of an individual's foot rolls and lifts up from the shoe sole.

The aforesaid centering means are configured especially such that, as is usual with flip-flops, they permit the sole of a foot to lift up during the rolling movement of the foot during walking, while still preventing lateral slipping and twisting of the shoe sole relative to the foot such that the shoe sole, when seen from a top view, always remains essentially in its pre-specified proper position under the sole of the foot whereby a big toe compartment can act as a corrective toe positioning aid to hold the big toe in its proper natural position.

In an embodiment of the invention, the aforesaid centering apparatus advantageously includes at least one pair of connecting straps that connect the shoe sole to the metatarsal strap and that run at an incline in opposite directions in order to center the shoe sole with respect to the metatarsal strap. The aforesaid connecting straps are in particular each inclined at an acute angle relative to a center longitudinal plane that runs upright through the shoe sole so that overall there is substantially a V-shaped arrangement of the connecting straps that provides the centering effect.

It is also possible for the connecting straps to be arranged in a completely different manner. For instance, the connecting straps could be spaced farther apart from one another at their fastening points on the shoe sole than at their connecting points to the metatarsal strap so that the result would essentially be a pitched roof-shaped arrangement of the connecting straps. However, in an embodiment of the invention the connecting straps are advantageously arranged in the opposite manner, i.e., the connecting straps are spaced farther apart from one another at their connecting points to the metatarsal strap than at their connecting points to the shoe sole.

The V-shaped spreading of the connecting straps can vary. An arrangement of the connecting straps at a spread angle of 45° to 150°, preferably from about 60° to 120°, and in particular from about 75° to 100° can be advantageous for effecting sufficiently strong centering of the foot and for not introducing into the metatarsal strap tensile forces that are too strong. The distance between the connecting points for connecting the connecting straps to the shoe sole is advantageously less than ⅔ of the distance between the connecting points for the metatarsal strap.

When viewed clockwise and seen in section through the metatarsal strap, it is advantageous that the connecting straps are connected to the metatarsal strap approximately in the area of 7 o'clock to 10 o'clock and 2 o'clock to 5 o'clock, preferably in the area of about 8 o'clock to 9 o'clock and 3 o'clock to 4 o'clock, in order to effect adequate centering of the foot, but also to permit the foot sole to lift up sufficiently from the shoe sole, which is characteristic of the feeling of wearing flip-flops.

The connecting straps can advantageously be embodied sufficiently elastic and extensible to attain both lifting up of the foot sole from the shoe sole and also adequate centering for the shoe sole relative to the foot of the wearer.

In order to prevent torsion of the connecting straps, the latter are embodied with sufficient width and are connected to the metatarsal strap and shoe sole across their entire width, wherein the width of the connecting straps can advantageously be in the range of ⅔ to the entire width of the metatarsal strap. More specifically, the width of the connecting straps is preferably be between 3 cm and 10 cm, and in particular 4 cm to 7 cm.

When viewed from the side of the sandal, the aforesaid connecting straps advantageously extend essentially vertically or at only a slight incline from the metatarsal strap downward to the shoe sole so that the section of the shoe sole centered between the connecting points for connecting the connecting straps to the shoe sole corresponds to the metatarsus so as to be aligned beneath the metatarsus.

In an embodiment of the invention, the lateral foot sole support segments of the metatarsal strap are not directly connected to the lateral edges of the shoe sole at their end segments, as is normally the case with a conventional upper sole portion. Rather, they are drawn inward and are connected to non-edge portions of the sole by the connecting straps so that the lateral foot sole support segments of the metatarsal strap are not connected to the lateral sole edges so that the metatarsal strap on the left and on the right in an area between about 3 o'clock and 9 o'clock or, more specifically, at about 9 o'clock and 3 o'clock can be stretched away and substantially upward from the shoe sole and spaced apart therefrom so as to exert a corresponding tightening force on the sole area of the metatarsus.

The aforesaid foot sole support segments of the metatarsal strap are drawn inward so as to be spaced apart from the shoe sole edges and towards the center region of the shoe interior that is delimited by the upper part of the metatarsal strap and the shoe sole, and due to this are positioned relative to the lateral edges of the foot sole in order to provide upright support there at the center region, specifically when the sole of the wearer's foot lifts up from the shoe sole during a rolling motion.

In an embodiment of the invention, tensioning means for tightening the metatarsal strap are provided so that the aforesaid lateral foot sole support segments of the metatarsal strap are able to be tightened inward and upward, as stated hereinbelow, in order to attain the desired support. The aforesaid tensioning means advantageously include length adjusting means for adjusting the length of the aforesaid metatarsal strap. In order to ensure simple operation, the tensioning means and/or the length adjusting means includes an actuating part on a top side of the metatarsal strap, or on an exterior side thereof, so as to face away from the shoe sole. For instance, the metatarsal strap can be fixed in a tightened position using a velcro fastener or similar retention means.

In an embodiment of the invention, at least one connecting point for connecting the shoe sole to the metatarsal strap is arranged spaced apart from the sole edges and inset from the sole edges toward the center of the shoe sole by an amount equal to at least ¼ of the width of the shoe sole, and preferably ⅓ of the width or more.

In order to be able to finely adjust the position of the big toe and precisely adjust the correcting forces acting thereon, an embodiment of the invention includes an adjusting apparatus for adjusting the position and/or orientation of the big toe compartment relative to the shoe sole. The apparatus is provided as a big toe strap that exerts a correcting force on the big toe toward the interior of the shoe. Instead of a big toe strap that completely encircles the big toe, alternatively embodied tensile/pressure means for applying a corrective force toward the interior of the shoe can also be provided, for instance in the form of a displaceably arranged bar that extends on a side of the big toe facing the adjacent toe. Alternatively or in addition to the above, the big toe adjusting apparatus on the sole could be borne transversely and adjustable with respect to the sole of the shoe. It is preferred that the aforesaid big toe strap is connected to the interior of the shoe sole at a fixed position so as to comfortably exert a corresponding corrective force on the big toe using longitudinal displacement. In an advantageous embodiment of the invention, tensioning means for tightening the big toe strap to the big toe are provided and include length adjusting means for adjusting the length of the aforesaid strap. The big toe strap is contemplated to include a tightenable velcro loop that can preferably be fixed to the shoe sole or to itself.

In order to attain an enhanced exercise effect for the muscles that control movement of the big toe, an embodiment of the invention is provided so that movement of the big toe when the foot rolls upward is essentially mechanically disconnected from the movement of the other toes so that the big toe provides a major source of balancing for the foot like that which is provided when walking barefoot and in which case the muscles that hold the big toe receive more intense exercise, all while the big toe is prevented from moving incorrectly towards the outside of the foot. The shoe sole is advantageously provided so that a big toe segment of the shoe sole is separated from an adjacent toe segment in the shoe sole by a notch in the shoe sole that runs in the longitudinal direction of the shoe, and is thus bendable in the rolling direction of the shoe sole as the wearer moves. Because of the notch in the sole in the longitudinal direction of the sole between the big toe and adjacent toes, the segment of the shoe sole that is disposed under the big toe is movable relative to the adjacent, stationary segment of the shoe sole that is beneath the adjacent toes, i.e., such segment is bendable upward and downward about a transverse axis without the aforesaid adjacent, stationary segment of the shoe sole for the adjacent toes also bending at the same time.

No direct transfer of force between torsion forces and bending forces occurs between the big toe segment of the shoe sole and the adjacent toes segment of the shoe sole. As such, the big toe is not assisted by the adjacent toe segment of the shoe sole when balancing the foot, thereby providing increased exercise for the muscles that control big toe movement. Due to the notch in the sole between the big toe and adjacent toes, walking in the shoe feels like walking barefoot because the big toe rolls up regardless of the other toes. At the same time, accommodating the big toe in the big toe compartment separately from the other toes in conjunction with the centering apparatus that centers the shoe sole alignment relative to the metatarsal strap ensures that the big toe does not project out towards the outside of the foot, but rather is held in its straight, natural, and proper position. Thus, though the aforesaid notch in the sole is provided at the stated orientation, the flip-flop and its sole have sufficient bending stiffness transversely, i.e. with respect to bending about a vertical axis that is transverse to the longitudinal axis of the flip flop, to fix the big toe towards the inside of the foot and to prevent its undesired movement to the outside of the foot.

The big toe compartment is advantageously provided in the form of an essentially cylindrical sleeve that is open toward the tip of the toe. Alternatively, a compartment can be provided that encircles the big toe on all sides and is closed at the tip of the toe so that, when seen from the end of the shoe, the big toe compartment roughly forms a nearly cylindrical hollow unit that is open to the side from which the toe is inserted and closed to the tip of the toe, and when seen in cross-section this cylindrical hollow unit is encircled by the sole and corresponding arches that run in a curve above the sole.

The notch in the sole that provides the desired mechanical decoupling of the big toe segment in the shoe sole from the adjacent toe segment in the shoe sole can be embodied differently than as discussed above. In this respect, the aforesaid notch in the sole is advantageously formed as a cut and/or a slit in the sole that essentially cuts fully into and separates the shoe sole from the tip of the shoe sole proximate the big toe in the longitudinal direction of the shoe sole until about the point when it reaches the metatarsophalangeal joint. This yields completely separated sole areas under the big toe and the adjacent toes, thus attaining maximum decoupling during the rolling movement. Instead of such a complete removal of material, it is also possible to leave a thin layer of material in the area of the notch in the sole, such that this layer does not interfere with mechanical decoupling or provides only minimal interference. It can especially be provided that a connecting membrane is provided in the area of the notch in the sole between the big toe segment and the adjacent toe segment on the shoe sole so as to join the two aforesaid segments to one another. The connecting membrane forms a seal that prevents dirt or liquid from entering the slit between the big toe and adjacent toes. In this case, compared to the material for the shoe sole, the aforesaid connecting membrane is significantly more extensible and, where necessary, also much thinner, and wherein the aforesaid connecting membrane may be embodied using a different material than the rest of the shoe sole. For instance, it would be possible to use an extensible, water-tight textile membrane, the extensibility of which does not interfere with the desired decoupling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral elevation and perspective view of a flip-flop sandal having a foot disposed therein, as seen from the outside side of the foot, in accordance with one advantageous embodiment of the invention;

FIG. 2 is a lateral elevation and perspective view of the sandal in FIG. 1, as seen from the outside of the foot;

FIG. 3 is a top view of the sandal from FIGS. 1 and 2, as seen from above and when fitted with a foot of a wearer;

FIG. 4 is a schematic section view through the sandal in the area of the metatarsal strap from FIG. 1 in accordance with the line A-A in FIG. 1;

FIG. 5 is a top view of the sole of the flip-flop sandal in accordance with one embodiment of the invention, according to which the sole has a notch between the big toe sole portion and adjacent toes sole portion; and,

FIG. 6 is a schematic section through the sandal in the area of the metatarsal strap from FIG. 1 in accordance with the line A-A in FIG. 1, including a strap connection that is in accordance with another advantageous embodiment of the invention and that has been modified with respect to FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The sandal 1 depicted in the Figures is embodied in the form of a flip-flop sandal and includes a shoe sole 2 and a separate big toe compartment 7 at its front end in the area of the toes, and as seen in FIG. 5, can be separated from the shoe section that surrounds the adjacent toes by a sole notch 8. As FIG. 5 illustrates, the sole notch 8 in the embodiment depicted is formed by a slit-like cut 10 in which the material of the shoe sole 2 is completely removed. The aforesaid cut 10 reaches from the tip of the shoe sole 2 to about the metatarsophalangeal joint and extends essentially parallel to the longitudinal direction of the shoe sole 2.

As FIGS. 1, 2, and 3 depict, the big toe compartment 7 is formed by a big toe strap 14 that is connected to the shoe sole segment 2 a beneath the big toe and is advantageously embodied with a modifiable length so that the position of the big toe can be adjusted exactly on the shoe sole 2. For instance, the big toe strap 14 can be tightened and fixed by means of a hook-and-loop closure 16. Where necessary, it is possible for the position of the big toe strap 14, and thus of the big toe compartment 7, to be adjustable relative to the shoe sole 2, and especially can be changed to be positioned transverse to the longitudinal direction of the sole, by means of suitable adjusting means in order to be able to exert different strength corrective forces 15 on the big toe towards the inside of the foot and therefore be able to adapt the sandal to defective positioning of the big toe.

A metatarsal strap 17 is provided in the area of the metatarsus, as shown in FIGS. 1, 2, and 3. The metatarsal strap 17 completely encircles the metatarsus and is embodied independent of the shoe sole 2 so as to be elevated above a surface of the sole 2 and to thereby receive the wearer's foot therein. The strap 17 includes two lateral foot sole support segments 18 and 19 that encircle and support the metatarsus so as to be supported at its sides adjacent the foot sole 2. The aforesaid foot sole support segments 18 and 19 are detached from the shoe sole 2 and in particular are not directly attached to the lateral edges of the shoe sole 2 so that the metatarsus is supported from below using lateral upwardly and inwardly oriented support forces 20. Because the aforesaid foot sole support segments 18 and 19 are not connected to the lateral edges of the shoe sole 2, it is specifically the metatarsal segment of the foot that is addressed with respect to the hallux valgus disorder whereby the metatarsus is supported and shaped by the support forces 20.

As FIG. 4 depicts, the metatarsal strap 17 is advantageously not connected at the lateral edges of the shoe sole 2 and extends across at least ¼ of the shoe sole width, and above shoe sole 2 so as to extend thereabove by at least ¼ of the height of the shoe sole 2 in order to be able to apply the desired support forces 20.

The metatarsal strap 17 has tensioning means 21 in the form of a length adjusting apparatus 22 in order to be able to fit the metatarsal strap 17 to different foot widths and to adjust the support force 20. The tensioning means 21 or length adjusting means 22 can for instance include a hook-and-loop closure 24 by means of which the overlapping segments of the strap 17 on top of the closure 24 are fixed to strap segments thereunder (see FIG. 4).

The aforesaid metatarsal strap 17 is joined via a centering apparatus 3 to the shoe sole 2 and is embodied such that the shoe sole 2 lifts up when the foot rolls up during walking but such that, at least when it returns to the ground, it remains positioned centered relative to the foot sole and cannot slip to the side or transversely. Because of this, the big toe compartment 7 acts as a corrective toe positioning aid so as to hold the big toe in its proper natural position.

In a refinement of the invention, the aforesaid centering apparatus 3 advantageously includes at least one pair of connecting straps 4, 5 that connect the shoe sole 2 to the metatarsal strap 17 and that run at an incline in opposite directions in order to center the shoe sole with respect to the metatarsal strap 17. In particular, the aforesaid connecting straps 4, 5 are each inclined at an acute angle relative to a center longitudinal plane that runs upright through the shoe sole 2 so that overall there is provided a substantially V-shaped arrangement of the connecting straps 4, 5 (see FIGS. 4 and 6).

In an embodiment of the invention, the connecting straps 4, 5 are advantageously arranged such that the connecting straps 4 and 5 are spaced farther apart from one another at their connecting points 6 to the metatarsal strap 17 than at their connecting points 9 to the shoe sole 2.

The arrangement of the connecting straps 4, 5 in the embodiment depicted in FIG. 4 is at a spread angle of about 90° in order to effect sufficiently strong centering and in order not to introduce tensile forces that are too strong into the strap 17. The distance between the connecting points 9 for connecting the connecting straps 4, 5 to the shoe sole 2 is advantageously less than ⅔ of the distance between the connecting points 6 for the strap 17.

The embodiment depicted in FIG. 6 depicts a comparatively more widely spread arrangement of the connecting straps 4 and 5, which in accordance with FIG. 6 are arranged in a V-shape at about a 120° angle.

It is advantageous when the connecting straps 4 and 5, as seen in section through the metatarsal strap 17 in FIGS. 4 and 6, are connected to the metatarsal strap 17 approximately in the area of 7 o'clock to 10 o'clock and 2 o'clock to 5 o'clock, preferably in the area of about 8 o'clock to 9 o'clock and 3 o'clock to 4 o'clock, in order to effect adequate centering of the foot, but also to permit sufficient lifting up of the foot sole from the shoe sole 2, which is characteristic of the known feeling of wearing flip-flops.

The embodiment in accordance with FIG. 4 depicts a connection of the connecting straps 4 and 5 to the metatarsal strap 17 in the area of about 9 o'clock and 3 o'clock, while the more widely spread arrangement in accordance with FIG. 6 has a connection in the area of about 7:30 and 4:30.

The connecting straps 4 and 5 are advantageously sufficiently elastic and extensible to attain both lifting up of the foot sole from the shoe sole 2 and also an adequate centering for the shoe sole 2.

In order to prevent torsion of the connecting straps 4 and 5, the latter are embodied with sufficient width and are connected to the metatarsal strap 17 and shoe sole 2 across their entire width, wherein the width of the connecting straps 4, 5 advantageously equals the width of the metatarsal strap 17. The width of the connecting straps 4, 5 is preferably between 4 cm and 7 cm.

When viewed from the side of the sandal 1, as shown in FIGS. 1 and 2, the aforesaid connecting straps 4, 5 advantageously extend essentially vertically or at only a slight incline from the metatarsal strap 17 downward to the shoe sole 2 so that the center point of the connecting points 9 for connecting the connecting straps 4, 5 to the shoe sole 2 corresponds to the metatarsus. 

1. A sandal comprising: a sole defining a longitudinal axis thereof, edges on either side of the longitudinal axis so as to provide a sole center portion therebetween within an interior of the sandal, and tip portions at each end of the longitudinal axis; a big toe compartment for separately accommodating the big toe separate from other toes of the foot; a metatarsal strap for supporting the metatarsus and having lateral foot sole support segments that are directed inward toward the sole center portion, the lateral foot sole support segments being unconnected to lateral edges of the sole; and a centering apparatus for centering the sandal sole relative to the metatarsal strap, the centering apparatus being connected to each of the sandal sole and the metatarsal strap so that the lateral foot sole support segments are positioned above the sandal sole so as to support the metatarsus of the foot of a wearer of the sandal when the wearer is walking.
 2. The sandal in accordance with claim 1, wherein, during a rolling movement of the foot occurring during walking, the sandal sole lifts upwardly toward the lateral foot sole support segments of the metatarsal strap without being twisted relative to the metatarsal strap and out of alignment with the foot of the wearer.
 3. The sandal in accordance with any one of the foregoing claims, the centering apparatus comprising at least one pair of connecting straps, each of the connecting straps being connected to the sandal sole and to the metatarsal strap, the connecting straps being disposed at an incline and in opposite directions relative to the metatarsal strap and the sandal sole.
 4. The sandal in accordance with claim 3, wherein the connecting straps are symmetrically inclined at an acute angle relative to a center longitudinal plane that runs upright through the shoe sole.
 5. The sandal in accordance with claim 4, wherein the connecting straps are inclined relative to one another in a V-shape at a spread angle from 45° to 150°.
 6. The sandal in accordance with claim 5, wherein the distance between the connection of each of the connecting straps to the sandal sole is less than ⅔ of the distance between connection of each of the connecting straps to the metatarsal strap.
 7. The sandal in accordance with claim 6, wherein the connecting straps, when seen in cross-section relative to the metatarsal strap, are each respectively connected to the metatarsal strap at substantially 7 o'clock to 10 o'clock and 2 o'clock to 5 o'clock.
 8. The sandal in accordance with claim 1, wherein points of connection for the centering apparatus are arranged so as to be spaced apart from the edges of the sandal sole by at least ¼ of the width of the sandal sole and are inwardly offset toward the center of the sandal sole.
 9. The sandal in accordance with claim 1, wherein the metatarsal strap comprises tensioning means for tightening the metatarsal strap.
 10. The sandal in accordance with claim 9, wherein the tensioning means comprises length adjusting means for adjusting the length of the metatarsal strap.
 11. The sandal in accordance with claim 1, wherein the foot sole support segments of the metatarsal strap are not directly connected to the sandal sole and are positioned over a segment of the sandal sole that is at least ¼ of the width of the sandal sole.
 12. The sandal in accordance with claim 11, further comprising a big toe strap for exerting a corrective force on the big toe towards the sandal interior.
 13. The sandal in accordance with claim 12, wherein the big toe strap forms at least part of the big toe compartment.
 14. The sandal in accordance with claim 13, further comprising tensioning means for tightening the big toe strap towards the sandal interior.
 15. The sandal in accordance with claim 14, wherein the tensioning means includes a length adjusting means for adjusting the length of the big toe strap.
 16. The sandal in accordance with either of claim 1 or 12, wherein the sandal sole comprises a big toe segment that is separated from an adjacent toe segment of the sandal sole by a notch in the sandal sole that runs in the longitudinal direction of the sandal and that can be bent independently in the rolling direction of the sandal so as to be independently movable about an axis which is transverse to the longitudinal axis of the sandal.
 17. The sandal in accordance with claim 16, wherein the notch is formed by a cut and/or slit in the sandal sole.
 18. The sandal in accordance with claim 17, wherein the notch comprises a length substantially defined as the distance from the tip of the sandal proximate the big toe compartment to the second joint in the big toe. 